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KTR 2280 Preliminary H 08/17/06
It is recommended that a COM be connected to the top antenna for good ground
communication and that the other COM be connected to the bottom antenna to provide
good airborne communications. If mounting antennas on the same side of the aircraft is
unavoidable, maintain the minimum allowable separation (8 feet).
The antenna should be mounted on a section of the aircraft that is horizontal during cruise
flight. The base of the antenna should be well bonded to the metal aircraft skin. Remove
any paint from around the mounting holes to ensure a good connection between the
antenna and the skin. The metal aircraft skin at the base of the antenna should extend a
minimum of twenty-four inches in every direction. This provides the ground plane required
for the antenna. Any less metallized area will result in reduced communication range at
some bearings around the aircraft and may increase interference to and from other
systems.
The COM transceiver performance depends heavily on the integrity of the electrical
bonding to the airframe and also the electrical integrity of the aircraft structure. If the
electrical resistance between an antenna and the aircraft or between adjacent skin panels
change intermittently, noisy communications may result.
Connect the antenna to the COM unit with 50 ohm coaxial cable, keeping the cable length
to a minimum and avoiding sharp bends in the cable. Keep the COM antenna cable as far
away from other antenna cables as possible and do not bundle several cables together.
Use Dow-Corning DC-4, or equivalent, on both inside and outside of the connector and
its mate as an effective barrier against moisture and to prevent corrosion.
2.3.4.2 NAVIGATION ANTENNAS
The NAV antenna should be well removed from other antennas, projections, engines or
propellers. It should have a clear line of sight area if possible. The antenna must be
mounted symmetrically with the center line of the aircraft. Avoid running other coaxial
cables and wires near the NAV antenna cable.
The VOR/LOC antenna with Glideslope is a two piece dipole with one part mounted on
each side of the vertical stabilizer. It should be installed on the upper section of the vertical
stabilizer of single finned aircraft and be at least 28 inches (measured vertically) from the
horizontal stabilizer.
On dual VOR/ILS installations, it is recommended that a splitter be used to divide signals
from a single VOR/LOC antenna into two or more receivers. Use double shielded cables
to reduce interference to the receivers.
Rev. 0, Aug/2006
Page 2-4
©Honeywell International Inc. Do not print without express permission of Honeywell
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